The overall goals of this project are to characterize cells of the murine immune system and determine the mechanism(s) of action and interaction among these cells in the generation and regulation of antibody responses in vitro to protein and synthetic amino acid antigens. Fluorescein conjugates of fowl gammaglobulin, hen egg lysozyme (HEL) and pigeon cytochrome C (PCC) and GAT will be used. A major unresolved problem in cellular immunlogy focuses on the nature of suppressor T cells (Ts cells). We have recently identified "Ts cells" in the spleen of antigen-primed nude mice; this observation provides the means to better understand Ts cells, their development, mechanism(s) of activation and action and their role in regulation of antibody responses, especially to antigens under MHC-linked immune response gene (Ir gene) control, such as HEL, PCC and GAT. Ts subsets that have been identified in normal and nude mice are Ts cells in virgin spleen and suppressor-inducer and suppressor-effector Ts cells in antigen-primed spleen. The objectives of this proposal are to characterize "Ts cells" in nude mice and compare them with Ts cells from normal mice in terms of: expression of membrane markers, such as Iat, Tind and Tsu; development and maturation; effects of thymus gland grafts on Ts cells in nude mice; effects of helper T cells on development of Ts cell subsets; and, antigen requirements for activation of Ts cells. We plan to determine the target cell and mechanism of action of products of these T cell subsets and to characterize membrane markers unique to Ts cell subsets (Iat, Tind and Tsu) by biochemical and molecular biological analysis. Lastly, we will clone these Ts cell subsets using a new procedure and characterize the clones by membrane markers, physiologic function and mechanism of action. These studies should provide new information on the origin, maturation, activation and mechanism of action of Ts cells and the characterization of unique markers expressed on T cells, such as Iat, Tind and Tsu. Since Ts cells are involved in the Ir gene control of responses to HEL, PCC and GAT, this study could provide new information concerning stimulation of helper and Ts cells by Ir gene controlled antigens in "nonresponder" animals and the mechanism of action of Ir genes.